Chapter 1 The Human Body: An Orientation

Anatomy – study of the structure and shape of the body and body parts and their relationship to each other Gross anatomy – study of large, easily observable structures Microscopic anatomy – study of very small structures Physiology – study of how the body and its parts function

Structural organization Atoms>cells>tissues>organs>organ systems>organism Cardiovascular heart, blood vessels – carries oxygen, nutrients Lymphatic lymph nodes, spleen – cleanse blood Respiratory lungs – supply oxygen Digestive stomach–breakdown and absorb food Urinary kidneys – rid body of waste Reproductive produce offspring Organ systems Integumentary skin – waterproofs, cushions, protects Skeletal bones – support and protection Muscular muscles – movement Nervous brain, spinal cord – fast control system Endocrine glands, hormones – slow control system

Necessary life functions Maintaining boundaries Movement Responsiveness (irritability) – ability to sense changes in environment and react to them Digestion Metabolism – chemical reactions that occur w/in cells Excretion – removing excreta (wastes) Reproduction Growth – increase in size

Survival needs Nutrients – chemicals used for energy and cell building Oxygen – energy reactions require oxygen Water – 60-80% of body weight Body temp maintained at about 37˚C (98˚F) Atmospheric pressure – breathing depends on appropriate pressure Too low = lower gas exchange

Homeostasis – body’s ability to maintain stable internal conditions 2 main regulating systems: nervous, endocrine Homeostatic control mechanisms have 3 components Receptor – responds to stimuli Sends info on by the afferent pathway Control center – determines level at which a variable is to be maintained, analyzes info, and determines response Sends info on by the efferent pathway Effector – provides the means for a response Negative feedback – slow/stop original stimulus – maintaining body temp Positive feedback – speed up/start Ex. blood clotting, birth

Anatomical Position – body’s standard position (arms down with palms forward) See page 16-17 to review terms

Directional terms (pg. 15) Superior (cranial) – head end Inferior (caudal) – tail end Anterior (ventral) – front, belly Posterior (dorsal) – back Medial – midline Lateral – outer Intermediate – btw medial and lateral Proximal – close to limb attachment Distal – farther from limb attachment Superficial (external) – body surface Deep (internal)

Body planes and sections Section – cut Plane – imaginary line where section is made Sagittal – lengthwise – divides into right and left parts Midsagittal – in half lengthwise Frontal – lengthwise – divides into anterior and posterior Aka coronal section Transverse – horizontal – divides into superior and inferior Aka cross section

Body cavities Dorsal body cavity Cranial cavity Spinal cavity Ventral body cavity Thoracic cavity – lungs, heart Mediastinum – separates lungs into right and left cavities – contains heart and trachea Abdominopelvic cavity Abdominal cavity – stomach/liver Pelvic cavity – repro./ bladder Divided into 9 regions (see pg 21) Umbilical – surrounding naval Epigastric – superior to umbilical Hypogastric – inferior to umbilical Right/left iliac (inguinal) – lateral to hypogastric Right/left lumbar – lateral to umbilical Right/left hypochondriac – lateral to epigastric